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Cross TT X Tt Give the genotypic and phenotypic ratios Male - spermatogenesis Occurs frequently Produce sperm cells Female - Oogenesis Occurs every 28 days Produce one egg Do not copy One mother cell produces four daughter cells Each daughter cell has haploid chromosome # (1/2 of what mother had) Occurs in sex cells (sperm and egg) 1. Interphase - mature cell ready for cell division 2. Prophase I - chromosomes are short, thick and double attached by centromere 3. Metaphase I - tetrads align at equator 4. Anaphase I - Tetrads split and move to opposite poles 5. Telophase I - events occur in the reverse of prophase I Don’t copy 6. Metaphase II - chromatids align at equator 7. Anaphase II - chromatids split and move to opposite poles 8. Telophase II - 4 cells with haploid #(new sperm and egg cells) Don’t Copy http://www.cellsalive.com/meiosis.htm Mitosis Asexual and sexual Identical cells produced Same #chromosomes (46) Body cells One Division Two cells made 20 minutes to one hour Meiosis Sexual cell division Cells different Different number of chromosomes (23) Sex cells Two divisions 4 cells made Occurs in days Crossing Over Genetic Recombination Trisomy - extra chromosome (down syndrome) Monosomy - lacking a chromosome (most lethal, Turner Syndrome) Triploidy - three sets of chromosomes Polyploidy - more than the usual number of chromosomes (rare in animals, common in plants) Gene - portion of DNA that is genetically active, controls traits Chromosome - Thread like, humans 23 pairs Haploid chromosome # (n) - single set of chromosomes Diploid chromosome # (2n) - two of each kind in a cell Homologous Chromosome - same Allele - one-half of a gene pair (T or t) Gamete - Sex cell, reproductive cell Sperm - male haploid # (Father) 23 chromosomes Egg - female haploid # (Mother) 23 chromosomes Zygote - fertilized egg by a sperm, diploid number (2n) = 46 chromosomes, 23 pairs •Organized photo of a person’s chromosome •Autosomes vs. sex chromosomes